Dedifferentiated chondrosarcoma of the middle finger arising from a solitary enchondroma: A case report

Figure 4 Histological findings of the amputated specimen. A: Macroscopically, the tumor has destroyed the bone cortex and is extended to the soft tissue below the skin. The tumor is a grayish-white hyaline cartilage component filling the medullary cavity with hemorrhage and necrosis. In the largest cross-section of the tumor (star), the high-grade dedifferentiated component (yellow) accounts for 10.2% of the tumor; B: Magnification × 4. There is an abrupt transition between the low-grade chondrosarcoma (lower side) and high-grade dedifferentiated sarcoma components (upper side; arrow); C: Magnification × 10. The cartilaginous portion of the tumor shows a grade 1 or grade 2 chondrosarcoma with bone destruction. Arrowheads show the hydroxyapatite artificial bone graft that was used 11 years ago; D: Magnification × 20. The high-grade dedifferentiated component shows mitoses and atypia. The lesion is composed of spindle cells arranged in a fascicular growth pattern, resembling a high-grade undifferentiated pleomorphic sarcoma.